Leakage-reducing device for steam-turbines.



0. JUNGGREN.

LEAKAGE REDUCING DEVICE FOR STEAM TURBINES.

APPLIOATION FILED JULY 26, 1909.

980,282. Patented Jan. 3, 1911.

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Inventor":

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UNITED STATES PATEN T OFFICE.

OSGAR'J'UNGGREN, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

LEAKAGE-REDUCING DEVICE FOR STEAM-TURBINES.

Specification of Letters Patent.

Patented Jan. 3, 1911.

Application filed July 26, 1909. Serial No. 509,573.

To all whom it may concern:

Beit known that I, OSCAR JUNGGREN, a

, citizen of the United States, residing at illustrative ofmy invention,Figure 1 is an axial section of a leakage reducing device; and Fig. 2 isa plan showing one of the carbon rings thereof.

3 indicates a casing which is made up of two or more parts. The plane ofdivision may be axial or otherwise. The casing may be separate'from theturbine or form an integral part or some portion thereof as best slutsthe requirements. The interior of the casin is provided with as manycells or cham ers 4 as there are leakage reducing rings, four beingshown in the present case. Each of these chambers is provided with twoflat alls 5 that are parallel to each other and perpendicularwithrespect to the shaft 6. I have used the term shaft for the sake ofsimplicity and mean by it the rotating member whether it bet-he shaftitself or some iart moving with it as a sleeve or wheel part forexample. In addition each chamber 1s provided with an annular wall 7which surrounds the packing ring but is separated therefrom by a largeclearance.

Located in each cell or chamber is a ring 8 made up of carbon orequivalent material which takes a high polish and will not scar orinjure the shaft when, fon. any reason, the parts seize. The ring ismade up of abutting sections or segments usually three or moredependingupon the diameter of the shaft. 1; have found butt-joints forthese segments to be the most :Ts atisfactory in practice. The bore ofthe rni is slightly greater in diameter than the siaft so that there isalways a small clearance; this clearance should, however, be as small aspossible consistent with free running under normal conditions. Throughthis clearance a certain limited amount of steamcan escape and to thisextent my invention is a leakage reducing device rather than a packingwhich as commonly understood means a device which is intended to preventall leakage. By making the shaft clearance exceedingly small the shaftcan run free and the relatively small amount of steamlost in this mannercan be taken into account in the design of the machine and will be aconstant factor rather than a variable one whichgradually gets worse astime goes on. .This is articularly importantwhere the leakage to econtrolled takes place in an inaccessible part of the machine or wherefor any reason the leakage reducing devices are given scant attention.

Surrounding the carbon segments is a thin band of metal 9 whose ends areunited by one or more springs 10, two in this case,

to make the pressure uniform. This band also covers the joints betweensegments and prevents radial leakage therethrough. The

and and spring serve to hold the segments together, and since the endsof said segments abut and there is a shaft clearance it follows thatthey are arch bound. That is to say the spring and band cannot force thesegments into engagementwith the shaft or rotating element. Of course ifthe shaft runs out of true or is moved to one side by any cause it mayenga e one of the segments or the adjacent en s of two of them but underno condition can the acking grip the shaft at two or more p aces. Eachring is arran ed to make a sliding fit in its cell or cham er. Thisshould be an easy fit but one which offers a certain limited amount offrictional resistance or opposition to movement. The total surfacepresented tothe shaft by each segment is considerably less than thetotal surface presented by it to the walls of the cell or chamber. Theobject of this is to preventas far as possible the tendency of the shaftto turn the packing ring within its cell.

It has been customary heretofore to anchor packing rings of the carbontype in a manner to prevent them from turning with the shaft. This isobjectionable for if for any reason they grip the shaft the action willbreak or damage the ring and may do serious damage to the shaft. In thepresent case the rings are not anchored and hence are entirely free toturn if the friction created by the shaft on the wall of thebore'exceeds that due to the engagement of the side faces of the packingrings with the walls of the cells. On the other hand just as soon .asthis happens the centrifugal force of the device etween stages, on thehigh pressure end of the turbine, or on the vacuum end of the turbine.as desired.

. If desired'steam for sealing the packing may be admitted by the pipe11 to the annular chamber 12 and drains 13 and 14 convey steam or waterfrom the chambers 15 and 16 respectively to stages of lower pressureinthe turbine or to the exhaust thereof.

It will be seen that in my improved structure all springs for pressingthe rings against the side walls of the cells or of the chambers havebeen omitted which makes for simplicity and certainty of operation. Bypermitting the rings to slide freely in planes perpendicular to theshaft axis they are free to adjust themselves with respect to the shaft,and since they are not anchored I against rotary motion they can, if thefricher, a segmental arch bound ring located in tion due to pressureexerted by the shaft ex- "ceeds a certain value, rotate therewith andthus free themselves automatically due to centrifugal force withoutdamage, and that the outside springs will ultimately return them toplace. The freeing of the carbon rings from the shaft in the mannerspecified is particularly important because said rings are relativelyfragile and excessive poundmg -or abnormal pressure w1ll-cause them tochip or crack which impairs their efi'ec t'iveness for the purposeintended.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention, together with theapparatus which I now consider to represent the best embodiment thereof;but I desire to have it understood that the apparatus shown is onlyillustrative, and that the invention can be carried out by other means.A

What claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1.. In a device. of the 'character'described, the combination of ashaft, a casing that surrounds the shaft and contains a chamsaid chamberwh'ose bore is slightly greater in diameter than the shaft, the sidefacesof the ring frictionally engaging the opposed walls of the chamber,and means which permit. the ring to free itself from the shaft when theshaft rotates said ring.

2. In a device of the character described,

both of whose side faces engage the Walls of the chamber, the area ofsaid faces being greater than the face presented to the shaft, and meanswhich normally preserve the .arch bound relation of the segments butwhich yield and permit the segments to rotate and at the same time moveoutwardly when the friction exerted by the shaft cxceeds that of thewalls of the casing on the mug. 3. In a device of the characterdescrlbed, the combination of a shaft, a caslng surrounding the-shaftand containlng a chamher having parallel walls, a segmental arch boundring located in the chamber and frictionally engaging both of saidwalls, the bore of the ring being slightly greater than the diameter ofthe shaft, said ring being free to rotate with the shaft, and springmeans carried by the ring which normally maintains the arch boundrelation'of the segments but which yield outwardly when the shaftrotates the packing and permit the segments to free themselves due tothe centrifugal force of their mass.

4. In a device of the character described, the combination of a casingthat incloses the shaft and contains a chamber, a carbon packing ringmounted in the chamber and composed of segments whose ends formbutt-joints, both of the side faces of the ring frictionally engagingthe walls of the chamber, a shaft the diameter of which is slightly lessthan the bore of the ring, a band inclosing the ring, and spring meanswhich unite the ends of the band and permit the segments to move awayfrom the shaft and free themselves whenthe ring is rotated by the shaft.

In a device of the character described, the combination of a casingcontaining chambers, rings mounted in the chambers.

which are free to rotate with the shaft and to move laterally withrespect thereto, a shaft which passes through the bores of the casingand rings, and means responsive to centrifugal force which permit therings to.

disefngage themselves from contact with the sha t.

6. In a device of the character described, the combination of a casingcontaining chambers, rings mounted in the chambers which are free torotate with the shaft and to move laterally with respect thereto, ashaft which passes through the. bores of the casing and rings, meansresponsive to centrifugal force which permit the rings to disengagethemselves from contact with the shaft, and drains communicating withthe chambers.

7. In a device of the character described, the combination of a shaft, acasing contain ing a chamber, a segmental arch bound ring surroundingthe shaft and mounted in the chamber wlth its lateral faces inengagement with the walls thereof, the bore of the ring being slightlylarger than the diameter of the shaft, said ring being free to rotatewith the shaft and to move laterally with respect thereto, and yieldingmeans acting on the periphery of the ring which tends OSCAR J UNGGREN.

Witnesses BENJAMIN B. HULL, HELEN ORFORD.

